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Thread: Renovated Basement - Size of Furnace Room okay without having to keep door open?

  1. #1
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    Renovated Basement - Size of Furnace Room okay without having to keep door open?

    Hey guys,

    I have a ~4200 sqft home and just finished off the basement. The furnace room has:

    - 2 furnaces
    - 1 water tank
    - 2 of the vanEE 200h air exchanger
    - 1 koolR Magnum wine cooling unit that vents into it

    Overall size of the room is ~1200 cubic feet, maybe a bit more since the ceilings are unfinished. A friend suggested that there might not be enough combustion air if I keep the door closed, which was the plan.

    Should I add some extra vents out the wall? We live in Toronto, so that would end up being quite cold in the winter, but want to make sure I have enough air circulating in the room.

    Thoughts?

    Tx!

  2. #2
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    There are measurements that can be takin to decide if there needed!

  3. #3
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    Why are the mechanical systems never thought about during a renovation. We look like the bad guys when equipment doesn’t work like it used to.

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    Thread Starter
    Thanks.. So it's not possible to estimate the space requirements? What would I need to do to measure. The contractor simply says "it's fine" but I've heard that before!

  5. #5
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    Quote Originally Posted by pbc View Post
    Thanks.. So it's not possible to estimate the space requirements? What would I need to do to measure. The contractor simply says "it's fine" but I've heard that before!
    Yes but you don’t estimate. Take the proper measurements and calculate what is required!

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    Quote Originally Posted by pbc View Post

    So it's not possible to estimate the space requirements?

    What would I need to do to measure.

    The contractor simply says "it's fine" but I've heard that before!
    -- Get WITH THE FLOW.!

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    -- Get WITH THE FLOW.!
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  7. #7
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    Are the furnaces sealed combustion? 2 white plastic pipes sticking outside?

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    Correct two white pipes going outside.

    Furnaces are Lennox EL296UHV units.

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    Quote Originally Posted by pbc View Post
    Correct two white pipes going outside.

    Furnaces are Lennox EL296UHV units.
    Okay, a bit more info, Lennox EL296UHV 045, so 44,000 btu's x 2 = 88,000. Read somewhere you need ~50 cubic feet of air per 1000 btu, so I need ~1,760 cubic feet.

    Room is exactly 121 sqft, 9' ceilings with 14" I-Joists, so say 1,210 cubic feet or thereabouts.

    Feels ~500 cubic feet too small, and not factoring in the 200H's (unsure if this helps or hurts the cause having them in there). Would I need to drill through the wall to the exterior and add say some 4 or 6" vents? Issue with that is of course the room would be freezing!

    Their HVAC contractor mentioned none of this unfortunately.

  10. #10
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    Furnace Spec

    Quote Originally Posted by pbc View Post
    Okay, a bit more info, Lennox EL296UHV 045, so 44,000 btu's x 2 = 88,000. Read somewhere you need ~50 cubic feet of air per 1000 btu, so I need ~1,760 cubic feet.

    Room is exactly 121 sqft, 9' ceilings with 14" I-Joists, so say 1,210 cubic feet or thereabouts.

    Feels ~500 cubic feet too small, and not factoring in the 200H's (unsure if this helps or hurts the cause having them in there). Would I need to drill through the wall to the exterior and add say some 4 or 6" vents? Issue with that is of course the room would be freezing!

    Their HVAC contractor mentioned none of this unfortunately.
    ASHRAE 62.2 - 2013
    Total ventilation and infiltration air = 156 CFM based on 4,200 square feet at total height of 17 feet.
    Infiltration is estimated as ~ 80 CFM Natural ( {2,800 cfm50 } T.B.D. by BLOWER DOOR TEST)
    MINIMUM Ventilation air should be 76 CFM.

    The HRV is NOT
    setup to feed the Mechanical Room.
    _________________________ ATTACHMENT _______
    _____ Room Layout EXAMPLE ________ _______

    465 to 1,300 CFM per Lennox spec.
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    Last edited by dan sw fl; 09-28-2020 at 09:14 AM.
    Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities

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    Quote Originally Posted by pecmsg View Post
    Yes but you don’t estimate. Take the proper measurements and calculate what is required!
    Outside of what I've done above, which is a simple calc on total BTU and total cubic feet, is there a way a layman can calculate what is required? My contractor is simply saying "it's fine", which I would imagine he's going to say as if any additional work is required he's not going to want to do it.

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    Quote Originally Posted by pbc View Post
    Outside of what I've done above, which is a simple calc on total BTU and total cubic feet, is there a way a layman can calculate what is required? My contractor is simply saying "it's fine", which I would imagine he's going to say as if any additional work is required he's not going to want to do it.
    Then maybe you need a different contractor.

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    Quote Originally Posted by pbc View Post
    Correct two white pipes going outside.

    Furnaces are Lennox EL296UHV units.
    2 white pipes for each furnace, or one pipe for each?
    Contractor locator map

    How-to-apply-for-Professional

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    Also, what is the BTU input of the water heater in that space?
    Instead of learning the tricks of the trade, learn the trade.

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    Thread Starter
    There is a black pipe and a white pipe for each furnace, both going outside.

    Water heater input BTU is 72000, also has a larger white pipe (4"?) going outside the house.

    ...and thanks a ton for all the helpful replies!

  16. #16
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    Okay, the water heater requires 3,600 cf of space for combustion air. Since your short. It needs to be gotten from other areas, whether that is from adjoining rooms, or the outside.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

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    Even with the large white pipe exiting from the water heater to the outside? I assumed that was for combustion air. Otherwise ... wouldn't every basement require a 20x20x9 foot room to house just a water heater, let alone the furnaces?

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    Quote Originally Posted by pbc View Post
    Even with the large white pipe exiting from the water heater to the outside? I assumed that was for combustion air. Otherwise ... wouldn't every basement require a 20x20x9 foot room to house just a water heater, let alone the furnaces?
    I would say most people have a 40,000 - 50,000 btuh input water heaters, requiring 2,000 - 2,500 sq ft.

    That PVC pipe on the water heater is for power venting the flue gas, not combustion air.
    Instead of learning the tricks of the trade, learn the trade.

  20. #19
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    Quote Originally Posted by pbc View Post
    Outside of what I've done above, which is a simple calc on total BTU and total cubic feet, is there a way a layman can calculate what is required? My contractor is simply saying "it's fine", which I would imagine he's going to say as if any additional work is required he's not going to want to do it.
    I have to ask Who's Doing this job, sounds like your digging for answers. If its a contractor and he / she doesn't know or cant look it up then...............seriously look for a different contractor!

  21. #20
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    Interesting, the vast majority of finished basements I see around here have maybe a 10x10 room, 10x15 max, for their "furnace rooms" where the water heaters and a furnace (or two) is held. Wonder if they have other methods of allowing air in that I simply didn't notice.

    Thinking about it more though, and just walking around in it, so the room is ~120 sqft or so, but the ceiling is not finished, nor do I intend to. So the 14" I-Joist ceilings basically run through the entire basement. Presumably then I have a ton more airflow than I'm thinking?

    Outside of calculating it based on BTU's/looking at the space, etc., is there an actual tool or measuring equipment of some sort that you guys use on a job site to measure this in some way? Or is it mostly done in the design phase.

    As I have no idea how to incorporate something like a ceiling that is not enclosed into the equation!

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